In most instances an unavailable USB drive is a result of file system inconsistencies.Please follow the directions to fix these inconsistencies (choose the section applicable to your Operating System)

In Windows, please do the following:

1. Plug the external hard drive into your Windows computer, allow the drive to be discovered. Run Chkdsk by changing focus of mouse to the icon represented by the hard disk right-click->Properties, select the Tools tab, click Check Now radio button. From the popup menu, check the box next to Automatically fix file system errors.

2. Unmount the external disk in Windows using "Safely Remove Hardware" from the task tray near the clock at the lower right corner.

3. Turn on your TonidoPlug , with only power and Ethernet cable attached, and wait for few minutes till blue LED turns green and now connect your USB drive.

I have another possible reason. It seems the enclosure I have for my external HDD doesn't always respond as expected when connected. I've had to unplug/replug the USB several times before the disk is properly recognised. I had the same issue (though less frequently) with the same disk connecting to my netbook. FWIW, the enclosure I have is from Acomdata.

My tonidounplugged is dead.After a power off and on usb disk no longer got recognized. Tried flashing but nothing, tried chkdsk nothing again.Now for some reason not even pinging plug. Dead. No blue light on when power on. No flashing lights at all!